Fused cutout with knee joint



Nov. 25, 1958 E, H, YONKERS 2,862,080

FUSED CUTOUT WITH KNEE JOINT Filed Nov. 19, 1956v 2 Sheets-Sheet 1 4f INVENTOR. 4 55d EDWARD h'. YON/(ERS A TTORNE YS Nov. 25, 1958 E. YONKERS FUSED CUTOUT WITH KNEE JOINT 2 Sheets-Sheet 2 Filed NOV. 19, 1956 INVENTOR.

EDWARD H. YON/(ERS ATTORNEYS United States Patent O FUSED CUTOUT WITH KNEE JOINT Edward H. Yonkers, Glencoe, Ill., assignor to Joslyn Mfg. & Supply Co., Chicago, Ill., a corporation of Illinois Application November 19, 1956, Serial No. 622,922

16 Claims. (Cl. 200-114) The present invention relates to fused cutouts, and has for one of its objects the provision of an improved cutout of the dropout type which is of simple and rugged construction, is thoroughly reliable in operation, and in which the fuse tube assembly may be easily and quickly mounted upon or detached from the spaced terminals of the insulator assembly. This invention is an improvement over the structure shown in United States Patent No. 2,493,433.

It is another object of the present invention to provide an improved cutout in which the fuse tube assembly is maintained in engagement with the upper contact until the fuse link has been extracted from the fuse tube.

According t-o another object of the invention, `the biasing means for the fuse extracting mechanism is housed within a link member pivotally secured to a fixed arm on the fuse tube and the link member cooperates with the fixed arm and with the fuse extracting arm to prevent the pivot from breaking to effect the dropout motion until the fuse link has been fully extracted.

It is a further object of the invention to provide a cutout of the character described wherein the fuse tube assembly includes at its lower end a pair of pivotally related parts and dropout movement of the assembly is effected by breaking the pivot incident to fuse rupture and structure is provided for preventing the pivot from breaking until the fuse link has been extracted from the fuse tube.

It is still another object of the invention to provide a fused cutout including pivotally connected par-ts at its lower end but which is nevertheless designed to be accommodated within the contacts illustrated in the aboveindentified Patent No. 2,493,433, thereby permitting interchangeable use of the cutout of the present invention or the cutout disclosed and claimed in the prior patent.

The invention, both as 4to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which:

Fig. l is a side view, partially broken away, illustrating an improved cutout characterized by the features of the present invention;

Fig. 2 is an enlarged fragmentary view, partially in section, illustrating the lower end of the fuse tube assembly shown with the fuse link intact and the assembly in its normal position;

Fig. 3 is a fragmentary side view further illustrating the lower portion of the fuse tube assembly showing the position of the hinged parts after rupture of the fuse link;

Fig. 4 is a sectional view taken along a line substantially corresponding to line 4 4 in Fig. 2, assuming, of course, that the latter showed the complete structure of the lower end of the fuse tube assembly; and

Fig. 5 is a fragmentary, perspective view of the link arm and lower supporting member of the fuse tube assembly.

2,862,080 Patented Nov. 25, 1958 Referring now to the drawings, and more particularly to Fig. 1 thereof, the present improved fused cutout is there illustrated as comprising the usual insulating support in the form of a petticoat insulator 10 having a center zone longitudinally thereof clampingly embraced by a bracket 11 which may be utilized in supporting the cutout upon a pole or another suitable supporting structure. At its respective upper and lower ends the insulating support 10 is provided with spaced apart upper and lower terminals or contacts indicated generally at 12 and 1S, respectively, and between which a fuse tube assembly 24 of the expulsion type is adapted to be supported.

Specifically, the upper terminal 12 comprises a conductive channel member of U-shaped cross section throughout its length having an integrally formed half collar 12a at one end thereof for embracing the collar seat provided at the upper end of the insulating support 10. This portion of the terminal 12 is clamped against the seating surface of the support 10 by means of a half coliar clamping member 13 and clamping screws 13a disposed upon opposite sides of the support 10. At its laterally extended end and on opposite sides, the upper terminal member 12 is provided with downwardly extending, parallel hood skirts 12e, the upper portions of which are arranged in meeting engagement with an overhanging lip 12e extending downwardly from the top portion of the member 12. Thus, the skirts 12e and the lip 12e cooperate to define a hooded -or partially enclosed space at the extended end of the terminal member 12 for receiving therewithin the upper end of the fuse -tube assembly 24. To prevent this end of the fuse tube assembly from being moved beyond a predetermined point longitudinally of the skirts 12e as the assembly is swung into its closed circuit position, a stop pin 12b is provided which vextends transversely between the two identified skirts. This pin is arranged to coact with a retaining element in the form of a double leaf spring catch member 14 to restrain the fuse tube assembly 24 against pivotal dropout movement to the ropen circuit position thereof. At one end, the two leaves of the spring 14 are anchored to the underside of the upper terminal member by means of a terminal screw 15 which is threaded through a reinforced topside portion of the terminal member. Upward travel of the retaining element 14 during dropout movement of the assembly 24 is limited by an adjustable stop screw 14b threaded through the top wall of the member 12 to engage the element 14 intermediate its ends. A clamping washer 17 and nut 16 threaded onto the screw 15 may be utilized to establish line wire connections with the upper terminal member.

The detachable fuse tube assembly 24 comprises the usual expulsioin fuse tube 25 formed of an inner layer of pressed fibre or the like, having good arc extinguishing gas evolving properties, and an outer layer of Bakeliteimpregnated paper having excellent insulating properties. At its upper end, this fuse tube is provided with a. terminal ferrule 28 having a threaded end portion for receiving the internally threaded terminal cap 29. This cap acts as a tube end part engageable with the retaining element 14 to restrain the fuse tube assembly against dropout movement. To insure seating of the cap in a fixed position and thus prevent variations in the distance between the upper end of the cap and the point of pivotal support of the fuse tube assembly, the ferrule 28 is provided with an inwardly directed shoulder 28a against which the lower rim 29a of the cap may be tightly screwed. The two terminal parts 28 and 29 are arranged to have the head 30a of a fuse link 30 clampingly held therebetween internally of the fuse tube 25. Specifically, the head 30a of the link is clamped against the upper end of the ferrule by means of coil spring 29h which extends downwardly from and is permanently attached to the top Wall of the cap 29 internally of the cap. This fuse link, which preferably is of the improved form disclosed and claimed in United States Patent No. 2,453,688, granted November 9, 1948, is provided with ar pigtail conductor 31 extending longitudinally of the tube 2S and out of the open lower end 25a of this tube.

The tube 25 is arranged to be supported by a laterally extending and conductive rigid supporting arm or member 26 which extends angularly downward from the lower end of the fuse tube 25 in the general direction of the lower terminal 18. This supporting arm is provided with a ferrule 26e through which the lower open end 25a of the fuse tube 25 is driven to provide a pressed t connection therebetween. As illustrated in Fig. 5, a portion of the supporting member 26 is recessed or cut away, as indicated at 2617, to provide a cradle for accommodating a link arm or hinge 34 which is mounted for pivotal movement with respect to the member 26 about a pivot pin 35 seated within aligned bearing openings in opposed wall portions 26e defining the cradle 2611.

In accordance with the present invention and as illustrated in Figs. 2 and 3, the supporting arm 26 further includes a pair of spaced apart projecting portions or extensions 26a extending beneath the link arm 34. The link arm includes a pair of vertical, parallel side walls 34a and 34h interconnected by a top wall 34C having a generally fiat portion 34d and a downwardly curving end region 34e. At the curved region 34e, the side walls protrude upwardly somewhat beyond the top wall in order to dene a guide channel the purpose of which will become clear as the description proceeds. The extensions 26a on the member 26, of course, are confined within the space 38 defined beneath the top wall and between the side walls.

Interengageable hinge parts respectively mounted upon the lower terminal 18 of the insulating support 10 and the end of the link arm are provided for pivotally supporting the fuse tube assembly 24 upon the insulating support 10. Specifically, the lower insulator terminal 18 is comprised of two half-cup parts 18a and 18h which are screw clamped to embrace the lowermost petticoat of the insulator 1t). The terminal part 18b is provided with hinge means in the form of two transversely spaced apart, hook-shaped brackets 19 having aligned trunnion receiving seats 19a formed therein which extend substantially normal to the longitudinal axis of the fuse tubing 25. Each of these brackets also includes a guide nose 19h which is utilized in the manner explained below to guide the hinge trunnions of the fuse tube assembly 24 into engagement with the seats 19a. The other part 18a of the lower terminal 18 is provided with a downwardly extending portion have spaced apart parallel sides 18e between which is supported the curved portion 20c of a U-shaped and twin leaf tensioning spring 2t). This portion of the terminal part 18a is also used to mount the clamping parts of a line terminal assembly 22 in an obvious manner. The U-shaped tensioning spring 20 is held assembled with the terminal part 18a by means of one or more assembly pins 18d xedly anchored to the bottom wall of the terminal part 18b.

As indicated above, the hinge parts of the fuse tube assembly 24 comprise a pair of trunnions 34)t and 34g located near the inwardly disposed end of the link arm 34 and extending transversely outward therefrom. More specifically, the trunnions 34f and 34g are formed integral with the side walls 34a and 3417, respectively, of the link arm. These trunnions are atted along the upper sides thereof, as indicated at 34h for the trunnion 341, in order to prevent removal from the trunnion seats or placement thereon except when the fuse tube assembly occupies its lowered or released position.

For the purpose of rapidly withdrawing the fuse link conductor or pigtail 31 from the fuse tube 25 upon rupture of the fusible element of the link, there is provided y a one-piece fuse extracting arm 33 which is die formed from flat, resilient strip metal stock, such, for example, as Phosphor bronze, is pivotally supported upon the link arm 34 and is substantially coextensive in length with the combined length of the link arm 34 and the supporting member 26. The main part of this fuse extracting arm is bent into the configuration shown in Figs. 1 and 2 of the drawings to have parallel extending intermediate and return bent portions 33a and 36, a loop-shaped end bridge 37 and an end pivot piece 33C which is bent around a pivot pin 33d seated within aligned bearing openings bored centrally of the trunnions 34f and 34g. Thus, the extracting arm 33 pivots about the axis of the trunnions and has the same axis of rotation as the fuse tube assembly 24. Intermediate the ends of the arm 33, means comprising a headed tie post 32 are provided for securely connecting the free end of the fuse link pigtail conductor 31 to the arm. Specifically, the post 32 is tixedly mounted upon the intermediate portion 33a of the arm and extends downwardly through a slot opening 36a in the return bent portion 36 of the arm. The dimensions of this slot opening are slightly greater than the cross-sectional dimensions of the post 32, thus permitting unrestricted movement of the arm portion 36 toward and away from the arm portion 33a. At its extended end, the post 32 flxedly supports a flat pigtail retaining head 32a having its ends 3219 bent slightly over the side edges of the arm portion 36. The tie post 32 and head 32a serve normally to stress the arm portion 36 toward the arm portion 33a, so that when a fuse pigtail conductor 31 is wrapped around the post 32 it is clamped against the underside of the head 32a by the arm portion 36.

In order to tension the fuse link conductor 31 through the arm 33, a multiple leaf tensioning spring 39 is disposed within the space 38 defined by the side walls and the top of the link arm 34. The leaf spring 39 is secured to the top wall 34e of the link arm by means of one or more rivets 39a. The free end 3% of the spring 39 bears against the head of a rivet 33e carried by the arm portion 33a of the fuse extracting arm 33 and, hence, urges the latter to pivot about the pin 33d in a clockwise direction as viewed in Figs. l and 2. The shape and construction of the spring 39 and of the fuse extracting arm 33 effectively provide the desired pull upon the fuse link conductor 31, preventing this conductor from being tensioned in excess of a predetermined pull, and insuring pigtail conductor extraction in the event the extracting arm 33 is partially pivoted away from the link arm 34 as a result of stretching of the pigtail conductor and fuse link during prolonged service of the cutout without refusing.

In order to provide for switch stick manipulation of the hinge trunnions 34] and 34g into engagement with the trunning seats of the brackets 19 the center part of the supporting member 26 is enlarged at a point adjacent the end of the arm to provide for the formation of an opening therein into which the hook of a switch stick may be inserted. This opening is comprised of a first part 27a of enlarged diameter through which the switch stick hook may be inserted, and an offset part 27]) of smaller diameter into which the shank portion of the hook may -be projected to prevent disengagement of the hook and the fuse tube assembly. To facilitate swinging of the fuse tube assembly into and out of its closed circuit position, the upper terminal member or ferrule 28 of this assembly is similarly provided with an enlarged and integrally formed loop 28h into which the hook of a switch stick may be readily inserted.

From the above explanation it will be apparent that when the fuse tube assembly 24 is detached from the terminals of the insulating support 10, the supporting arm26 and the extracting arm 33 are freely rotatable relative to each other. When it is desired to fuse the assembly 24, the terminal cap 29 is unscrewed from the ferrule 28 and a fuse link 30 inserted within the chamber of the tube 25 so that the pigtail conductor 31 thereof projects out of the open lower end 25a of the tube. Following this operation, and with the extracting arm 33 firmly engaged against the supporting arm 26, the projecting end of the conductor 31 is carried over the bridge portion 37 of this arm, tensioned and wrapped around the tie post 32 between the arm portion 36 and the head 32a. One or more turns may be taken around the post 32 as desired. As the turns are taken around the post 32. the arm part 36 is moved toward the arm part 33a, thus deforming the connected parts 33a, 37 and 36 so that the turns are tightly squeezed between the arm part 36 and the head 32a, thereby frictionally to hold the conductor turns against slippage. Thus, the pigtail conductor serves tightly to hold the arm 33 in engagement with the underside of the supporting arm 26. Tensioning of the pigtail conductor 31 in the manner just described locks the link arm 34 and the supporting member 26 so that these elements cooperate to form a continuous support for the lower end of the assembly 24. Thus, when the pigtail conductor is tensioned, the link arm 34 tends to pivot about the pin 35 in a counterclockwise direction as viewed in Fig. 2, but this pivoting action is limited by engagement of the edges 34i and 34k of the side walls 34a and 34b on the link arm with abutting shoulders 26]c on the supporting member 26. With the edges 34i and 34k in engagement with the shoulders 26f, the forked end of the supporting member 26 formed by the extensions 26a extends into the space 38 in the link arm 34. The extracting arm tensioning spring 39, of course, extends between the extensions 26a and acts upon the extracting arm 33 to tension the pigtail conductor 31. After the described operations are completed, the terminal cap 29 may be threaded onto the ferrule 28 until the cap rim 29a abuts the shoulder 28a, thereby to establish the exact desired distance between the top of the cap and the axis of the trunnions 26e` and 26d. As the cap 29 is screwed onto the ferrule 28, the spring 29b is compressed to clamp the head 30a of the fuse link tightly against the upper end of the ferrule.

In order to mount the fuse tube assembly 24 upon the terminals of the insulating support 10, the hook of a switch stick is first inserted through the opening 27a to bring the shank portion of the hook into registry with the opening part 27b of reduced diameter. Interlocking of the hook shank with the sides of the small diameter opening 27b serves to prevent inadvertent removal of the assembly 24 from the end of the switch stick. In this regard it is noted that the switch hook opening is positioned along the supporting arm 26 adjacent the extended end thereof so that as the switch hook is elevated to raise the assembly 24, the center of gravity of the assembly is well below the hook, thus providing for maintenance of the interlocked connection between the hook and the small diameter opening 27b, and for easy manipulation of the trunnions 34)c and 34g into engagement with the brackets 19 of the lower terminal 18. As these trunnions are manipulated to bring the same into engagement with the identified brackets, they are first engaged with the guide noses 19b of the brackets. Concurrently with such engagement, the upturned lip h of the biasing spring 20 engages the top wall 34C of the link arm 34. Thus, as the assembly 24 is manipulated to push the extended end of the link arm 34 toward the brackets 19, the spring 20, through its engagement with the upper surface of the wall 34e, functions to guide the trunnions 34f and 34g into seating engagement with the seats 19a in the brackets 19.

After the assembly 24 is thus pivotally mounted upon the lower terminal 18 of the insulating support 10, the hook of the switch stick may be withdrawn from the openings 27a and 27b and inserted into the opening of the loop 28b for the purpose of rotating the assembly 24 about the trunnions 34f and 34g into its closed circuit position. As the fuse tube assembly 24 is rotated in a counterclockwise direction as viewed in Fig. l to its closed circuit position, the tongue 20b of the biasing spring 20 rides up the surface portions 34e and 34d of the wall 34C and is guided within the channel formed by the upwardly protruding portions of the side walls 34a and 34b. Thus, the spring 20 is caused to react between the support 10 and the link arm 34 to perform two additional functions. First, it forces the trunnions 34f and 34g into pressure engagement with the seats 19a of the brackets 19 to hold the assembly 24 in position with the fuse tube end part 29 interlockingly engaging the retaining element 14. Secondly, it biases the link arm 34 in a direction tending to pivot the fuse tube assembly 24 in a clockwise direction as viewed in Fig. l. The pressure engagement between the two identified trunnions and their engaging brackets serves accurately to center the upper end of the fuse tube assembly 24 relative to the front or entrance opening between the parallel skirts 12e of the upper terminal 12. Thus, the upper end of the assembly 24 is, through the action of the spring 20, forced into a setting such that regardless of the direction from which the upward pivoting force is imposed upon the assembly, it will move between the parallel skirts 12e during the tinal pivotal movement of the assembly into its closed circuit position. As the tube end part 29 moves between the skirts 12C, it engages the catch portion 14a of the retaining element 14 and rides beneath this portion of the element until it is brought to bear against the stop part 12b. During iinal movement of the tube end part 29 toward the stop part 12b, the tube end part 29 rides beneath the lip 14a and seats against the underside of the element 14 to deform this element upward about -the end of the stop screw 14b. With the spring element thus deformed, it exerts a thrust longitudinally of the tube 25 having a component which tends to seat the trunnions 34 and 34g firmly within the seats 19a of the brackets 19. The upper end of the fuse tube assembly is prevented from rotating away from the closed circuit position thereof through its engagement with the lip 14a of the element 14.

With the fuse tube assembly 24 seated within the terminals 12 and 18, the spring 20 tends to break the knee joint existing between the link arm 34 and the rigid supporting member 26 since this spring exerts a force on the link arm tending to pivot it in a clockwise direction as viewed in Figs. l and 2 while the upper end of the fuse tube assembly is held by the retaining element 14. The knee joint is prevented from breaking, however, by the coaction between the upper surface of the arm portion 33a of the fuse extracting arm 33 and the integral forked extensions 26a on the supporting member 26. Thus, as long as the fuse pigtail conductor 31 is intact, the extracting arm 33 is held in the position illustrated in Figs. l and 2 where it extends along and lies immediately adjacent the underside of the supporting member 26 to retain the extensions 26a within the space 38 in the link arm 34.

Thus, the fuse tube assembly 24 is iixedly mounted upon the insulating support 10 to provide a fused current path between the two terminals 12 and 18. Specifically, this path extends from the terminal screw 15 through the conductive arm 12 and the spring 14 to the terminal cap 29. From this point, the conductive path extends through the fusible element of the link 30 by way of the flexible pigtail conductor 31, the extracting arm 33, the link arm 34, the spring 20, the brackets 19 and the conductive terminal parts 18a and 18b to the line terminal assembly 22. It will be noted that the spring 14 thrusting down on the fuse tube and the spring 20 thrusting against the top wall 34e of the link arm 34 serve to hold all contacting parts of the fuse tube assembly and insulator terminals in pressure engagement, thereby to minimize contact resistance therebetween.

So long as current How over the described conductive path between the terminals 12 and 1S does not exceed the current-time fusing characteristic of the link 30, the fusible element within the link 30 serves mechanically to hold the extracting arm 33 in its set position against the underside of the supporting arm 26. When, however, this fusible element is required to carry current in excess of a predetermined magnitude for more than la predetermined interval, it is ruptured to relieve the holding force imposed upon the extracting arm 33 through the pigtail 31. The spring 39, in reacting between the link arm 34 and the upper surface of the fuse extracting arm 33, is thus rendered operative rapidly to rotate the arm 33 downwardly about the pivot pin 33d, thereby to withdraw the pigtail conductor 31 from the lower end of the fuse tube 25. In this regard it is noted that the arm 33 is of substantial length, such that rotation thereof through a relatively small angle produces a relatively large displacement between the bridge end 3'7 thereof and the lower end of the tube 25. Further, this arm is of small mass and hence has little inertia, thus insuring rapid acceleration of the bridge end 37 thereof away from the lower end of the fuse tube 25. In fact, the arm 33 and the spring 39 are preferably so designed that the are is suiciently elongated during the first voltage half cycle following fuse rupture to prevent breakdown of the gap during the next succeeding voltage half cycle. Further, the length of the extracting arm 33 and the angle of movement ofthe bridge end 37 thereof is such that, under any and all conditions of fuse rupture, all of the pigtail conductor 31 and the lower unfused Segment of the fuse link are completely removed at high speed from the bore of the fuse tube to hang downwardly in alignment with the long axis of the insulating support 10.

As the arm 33 is rotated to a position approximately normal to the longitudinal axis of the support 10, that is to a horizontal position as viewed in the drawings, the upper surface of the arm portion 33a thereof tends to move away from the spring part 39h and continued movement of the extracting arm to the dotted line position shown in Fig. 2 clears the way for movement of the extensions 26a in order to break the knee joint between the link arm 34 and the support member 26.

It should be emphasized that the knee joint connection cannot be broken until the extracting arm reachesthe dotted line position due to the fact that, prior to this time, the upper surface of the extracting arm remains in engagement with the extensions 26a and, hence, prevents pivotal movement between the link arm 34 and the supporting member 26 and maintains the fuse tube assembly seated within the terminals 12 and 18. Moreover, by the time the described position has been reached the end of the pigtail conductor 31 has been completely extracted from the open lower end of the fuse tube 25. This arrangement is to be distignuished from conventional dropout cutouts wherein the dropout movement of the fuse tube assembly and the pigtail conductor extraction are initiated at the same time and occur simultaneously.

When the extracting arm 33 has moved to the dotted line position shown in Fig. 2, the tongue 20h of the spring 20 exerts a force on the link arm 34 to pivot the latter about the trunnion seats 19a in a clockwise direction. As illustrated in Fig. 3, this pivotal movement is limited by engagement of a dog projection 34m on the link arm with an edge portion 26g at the bottom of the recess 26b in the support member 26. Breaking of the knee joint is accompanied by downward movement of the tube end part 29 away from the retaining element 14, until a point is reached where the catch 14a no longer engages the side of the tube end part 29. Thus, the fuse tube assembly 24 is released for downward pivotal dropout motion about the axis of the trunnions 34j and 34g under the influence of gravity forces acting thereon.

From the above explanationit will be apparentthat dropout movement of the fuse tube assembly 24 is effected primarily by breaking the knee connection in the lower support of the assembly to free the upper end of the assembly from the retaining element 14. The importance of exactly positioning the cap 29 relative to the other parts of the assembly, i. e., in a position such that its rim 29a tightly seats against the shoulder 28a, thus becomes apparent. In this regard it is noted that the amount of pivotal movement between the link arm 34 and the supporting member 26 is so related to the permissible downward travel of the retaining element 14 that release of the tube end part 29 from the retaining element is assured during the described breaking of the knee connection. The downward travel of the retaining element 14 may, by suitable adjustment of the screw Mb through the terminal part 12, be limited as required to insure full release of the tube end part 29 from the element 14 as the link arm is pivoted about the supporting member 26.

Two of the problems involved in the construction of any cutout embodying a fuse extracting mechanism are those of preventing the fusible element of the link from being overtensioned to change the operating characteristics of the link and of obtaining fuse remnant extraction upon fuse rupture even though the extracting arm has moved partially away from its fuse tensioning position as a result of stretching of the fusible element and pigtail conductor of the link. The critical tension beyond which the fusible element of the link should not be tensioned varies for links of different sizes or current ratings. In general, however, it is safe to employ a pull not exceeding 12 pounds upon the pigtail conductor of a link of the smallest rating. In the illustrated embodiment of the invention, the spring 39 and the extracting arm 33 are so designed that the pull exerted upon the pigtail conductor 31 is limited not to exceed a predetermined value. In this connection, it should be observed that the only force applied to the conductor 31 is that exerted by the spring 39 since the force exerted by the lower contact spring 2i) is not transmitted to the fuse extracting arm 33. This feature is particularly important because it allows the use of a high pressure spring on the current carrying elements of the lower terminal assembly. Another important feature of the present invention resides in the fact that the current ow in the conductor 31 is transferred to the lower Contact 18 without passing through the pivot connection between the fuse extracting arm 33 and the link arm 34. Thus, current passes through the silver contact 33e on the extracting arm and through a copper sheet or layer of the spring 39 tothe link arm 34, thus preventing fusing of the pivot connection at pin 33d.

In accordance with a further feature of the invention, the fuse link tensioning facilities are so arranged that force is imposed upon the extracting arm 33 throughout the major portion but not the entire range of angular movement thereof. Thus, the configuration of the extracting arm 33 and the spring 39 is such that during rotation of the arm 33 to extract the conductor 31 from the fuse tube, the tongue 3% of the spring 39 is biased against these parts until the arm 33 is rotated through an appreciable angle or to a position substantially normal to the support 1t?. Further, the biasing force acting upon the extracting arm 33 remains substantially constant and at a high value during movement of the arm 33 through the major portion of the angle through which it is rotated when the fusible element 3@ of the fuse link ruptures. This being true, it follows that even though the arm 33 is permitted to rotate partially away from the supporting arm 26 due to stretch of the pigtail conductor 31 and the fusible element of the link, the arm 33 will nevertheless be rapidly rotated to effect arc elongation and fuse remnant extraction when the fusible element of the link ruptures. Moreover, since the extracting arm does not permit the knee joint to be broken until it has been r-otated through an angle of approximately forty-five degrees or to a position substantially normal to the support 10, the knee joint will also remain rigid in spite of stretch of the pigtail conductor 31 and of the fusible element 30 of the fuse link. The lips of the extensions 26a on the Support arm engage the extracting arm 33 after the knee joint is broken and the relatively large force of spring 20 is then transmitted to the arm 33 in order to complete its pivoting movement. Thus, the described features all contribute to fast and positive removal of the pigtail conductor 31 from the fuse tube 25 when the fusible element of the link 30 is ruptured, while at the same time preventing the knee joint from breaking until the conductor 31 has been extracted from the fuse tube by a distance sufficient to draw a relatively long arc within the tube. This long arc insures the generation of enough gases to effect the expulsion before the dropout motion takes place. In many prior art designs, where only a short arc is drawn before thedropout action, insufficient gases are generated, particularly in the case of low current arcs, and the circuit is not interrupted at the time the cutout begins its dropout movement. Under the latter conditions arcing takes place between the upper terminal and the upper end of the fuse tube and this arcing is frequently transferred to adjacent line equipment or the like. The present invention avoids this condition by insuring that the circuit is interrupted before the upper end of the fuse tube is released from the upper terminal 12.

It should also be observed that the link arm 34 and the supporting member 26 are so dimensioned and constructed that the fuse tube assembly 24 will lit within the terminals illustrated in the Patent No. 2,493,433 identified above. Thus, the fused cutout of the present invention may be employed to replace that shown in the prior patent without requiring a new set of terminal fittings or the like.

While a particular embodiment of the invention has been described, it will be understood that various modifications may be made therein which are within the true spirit and scope of the invention as defined in the appended claims.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. A cutout of the dropout type comprising a support, a retaining element carried by said support, a fuse tube assembly including a fuse tube provided at one end with a part engageable with said element to restrain said assembly against dropout'movement, a supporting member rigidly connected to said fuse tube near its other end, a link arm pivotally connected to said supporting member to provide a knee joint, pivot means on said link arm, non-movable supporting means fixedly carried by said support for supporting said pivot means for pivotal movement to move said assembly away from said retaining element, a rst spring on said supporting means acting upon said link arm in a direction tending to produce pivotal dropout movement of said assembly, said fuse tube, supporting member, link arm and pivot means being movable as a unit with respect to said supporting means to release said part from said element and thus permit pivotal dropout movement of said assembly, said assembly including a fuse extracting arm pivotally mounted on said link arm and normally cooperating with said link arm and with said supporting member to prevent said knee joint from breaking, a fuse link extending through said fuse tube and secured to said fuse extracting arm, and a leaf spring having a first tongue engaging the link arm and a second tongue engaging the fuse extracting arm and tending to pivot the fuse extracting arm in a direction to extract the fuse link from the fuse tube in the event that the fuse link is ruptured in order to draw an arc between the ruptured ends of the fuse link and thereafter to permit said knee joint to break, thereby to permit pivotal dropout movement of said assembly,

said leaf spring being efIective to tension the fuse link prior to rupture independently of the force applied to the link arm by the rst spring.

2. A cutout of the dropout type comprising a support, a retaining element carried by said support, a fuse tube assembly including a fuse tube provided at one end with a part engageable with said element to restrain said assembly against dropout movement, a supporting member rigidly connected to said fuse tube, a link arm pivotally connected to said supporting member to provide a `knee joint, pivot means on said arm spaced from said knee joint, non-movable supporting means xedly carried.

by said support for supporting said pivot means for pivotal movement to move said assembly away from said retaining element, a first spring on said supporting means acting upon said link arm in a direction tending to produce pivotal dropout movement of said assembly, said fuse tube, supporting member, link arm and pivot means being movable as a unit with respect to said supporting means to release said part from sai-d element and thus permit pivotal dropout movement of said assembly, said assembly including a fuse extracting arm pivotally mounted on said link arm and extending along and cooperating with said link arm and said supporting member normally to prevent said knee joint from breaking, a fuse link extending through said fuse tube and secured to said fuse extracting arm, a leaf spring having a first tongue engaging the link arm and a second tongue engaging the fuse extracting arm and tending to pivot the fuse extracting arm in a direction to extract the fuse link from the fuse tube in the event that the fusel link is ruptured in order to draw an arc between the ruptured ends of the fuse link and thereafter to permit said knee joint to break, thereby to permit pivotal dropout movement of said assembly, and a contact on said fuse extracting arm in engagement with said second tongue in order to provide a low resistance path from the fuse link to said supporting means through the contact, the leaf spring and the link arm, thereby avoiding current flow through said knee joint.

3. A cutout of the dropout type comprising a support having upper and lower contacts, a retaining element carried by sai-d upper contact, a fuse tube assembly including a fuse tube provided at its upper end with a part engageable with said element to restrain said assembly against dropout movement, a supporting member rigidly connected near the lower end of said fuse tube, a link arm pivotally connected to said supporting member to provide a knee joint, means for supporting said link arm on said lower contact for pivotal movement to move said assembly away from said retaining element and thus permit pivotal dropout movement of said assembly, a biasing spring carried by said support and acting on said link arm in a direction tending to break said knee joint, said assembly including a fuse extracting arm normally cooperating with said link arm and said supporting member to prevent said knee joint from breaking, a fuse link extending through said fuse tube and secured to said fuse extracting arm, a leaf spring having a first tongue carried by the link arm and a second tongue engaging the fuse extracting arm and tending to pivot the fuse extracting arm in a ydirection to extract the fuse link from the fuse tube in the event that the fuse link is ruptured in order to draw an arc between the ruptured ends of the fuse link and thereafter to permit said knee joint to break, thereby to permit pivotal dropout movement of said assembly, said leaf spring being effective to tension the fuse link prior to rupture independently of the force applied to the link arm by said biasing spring, and a contact on said fuse extracting arm in engagement with said second tongue in order to provide a low resistance path from the fuse link to said supporting means through the contact, the leaf spring and the link arm, thereby avoiding current flow through said knee joint.

4.. A cutout of the dropout type comprising a support having upper and lower contacts, a retaining element carried by said upper contact, a fuse tube assembly including a fuse tube provided at its upper end with a part engageable with said element to restrain said assembly against dropout movement, a supporting member rigidly connected near the lower end of said fuse tube, a link arm pivotally connected to said supporting member to form a knee joint, means for supporting said assembly for pivotal movement on said lower contact to move said assembly away from said retaining element and thus permit pivotal dropout movement of said assembly, a first spring carried by said support and acting on the upper surface of said link arm in a direction tending to break said knee joint, said assembly including a fuse extracting arm pivotally mounted on said link arm and extending beneath both said link arm and said supporting member and normally cooperating with said link arm and said supporting member to prevent said knee joint from breaking, a fuse link extending through said fuse tube and secured to said fuse extracting arm, a leaf spring secured to the underside of said link arm and having a tongue portion in engagement with the fuse extracting arm for exerting a force tending to pivot the fuse extracting arm in a direction to extract the fuse link from the fuse tube in the event that the fuse link is ruptured in order to draw an arc between the ruptured ends of the fuse link and thereafter to permit said knee joint to break, thereby to permit pivotal dropout of movement of said assembly, said leaf spring being effective to tension the fuse link prior to rupture independently of the force applied tothe link arm by said rst spring.

5. A cutout of the dropout type comprising a support, a retaining element carried by said support, a fuse tube assembly including a fuse tube provided at one end with a part engageable with said element to restrain said assembly against dropout movement,'a supporting member rigidly connected to said fuse tube near its other end, a link arm pivotally connected to said supporting member to provide a knee joint, a pair of trunnions on said arm spaced `from said knee joint, non-movable supporting means xedly carried by said support for supporting said trunnions for pivotal movement to move said assembly away from said retaining element, said fuse tube, supporting member and link arm being movable as a unit with respect to said supporting means to release said part from said element and thus permit pivotal dropout movement of said assembly, said supporting member having an integral portion extending beyond said knee joint, said assembly including a fuse extracting arm pivotally mounted on said link arm and extending along said link arm and said supporting member and normally cooperating with said portion to prevent pivotal movement between said link arm and said supporting member, a fuse link extending through said fuse tube and secured to said fuse extracting arm, and biasing means disposed between said fuse extracting arm and said link arm to pivot said fuse extracting arm when said fuse link is ruptured in order to extract the fuse link from the fuse tube and thereafter to free said link arm and said supporting member for pivotal movement, thereby to permit pivotal dropout movement of said assembly.

6. A cutout of the dropout type comprising a support, a retaining element carried by said support, a fuse tube assembly including a fuse tube provided at one end with a part engageable with said element to restrain said assembly against dropout movement, a supporting member rigidly connected to said fuse tube near its other end, a link arm pivotally connected to said supporting member to provide a knee joint, a pair of coaxial trunnions on said arm spaced from said knee joint, non-movable supporting means xedly carried by said support for supporting said trunnions for pivotal movement to move said assembly away from said retaining element, said fuse tube, supporting member and link arm being movable as a unit with respect to said supporting means to release said part from said element and thus permit pivotal dropout movement of said assembly, said supporting member having a pair of spaced apart, integral extensions extending beyond said knee joint, said assembly including a fuse extracting arm pivotally mounted on said link arm for pivotal movement about the axis of said trunnions, said fuse extracting arm cooperating with said extensions to prevent pivotal movement between said link arm and said supporting member, a fuse link extending through said fuse tube and secured to said fuse extracting arm, and biasing means disposed between said fuse extracting arm and said link arm to pivot said fuse extracting arm when said fuse link is ruptured in order to extract the fuse link from the fuse tube and thereafter to free said link arm and said supporting member for pivotal movement, thereby to permit pivotal dropout movement of said assembly.

7. A cutout of the dropout type comprising a support having upper and lower contacts, a retaining element carried by said upper contact, a fuse tube assembly including a fuse tube provided at its upper end with a part cngageable with said element to restrain said assembly against dropout movement, a supporting member rigidly connected near the lower end of said fuse tube, a link arm pivotally connected to said supporting member to provide a knee joint, means for supporting said assembly for pivotal movement on said lower contact to move said assembly away from said retaining element and thus permit pivotal dropout movement of said assembly, said supporting means having a portion extending beyond said knee joint and into overlapping relationship with said link arm, a fuse extracting arm pivotally mounted on said link arm and cooperating with said portion to prevent pivotal movement between said link arm and said supporting member, a fuse link extending through said fuse tube and secured to said fuse extracting arm, and biasing means disposed between said fuse extracting arm and said link arm to pivot said fuse extracting arm when said fuse link is ruptured in order to extract the fuse link from the fuse tube and thereafterto permit pivotal movement between said link arm and said supporting member, thereby to permit pivotal dropout movement of said` assembly.

8. A cutout of the dropout type comprising a support having upper and 'lower contacts, a retaining element carried by said upper contact, a fuse tube assembly including a fuse tube provided at its upper end with a part engageable with said element to restrain said assembly against dropout movement, a supporting member rigidly connected near the lower end of said fuse tube, a link arm pivotally cormected to said supporting member to provide a knee joint, means for supporting said assembly for pivotal movement on said lower contact to move said assembly away from said retaining element an-d thus permit pivotal drop-out movement of said assembly, said supporting means 4having a portion extending beyond said knee joint, said assembly including a fuse extracting arm normally cooperating with said portion to prevent pivotal movement between said link arm and said supporting member, a fuse link extending through said fuse tube and secured to said fuse extracting arm, and means for causing said fuse extracting arm to extract the fuse link from the fuse tube when said fuse link is ruptured and thereafter to permit pivotal movement between said link arm and said supporting member, thereby to permit pivotal dropout movement of said assembly.

9. A cutout of the dropout type comprising a support having upper and lower contacts, a retaining element carried by said upper contact, a fuse tube assembly including Ia fuse tube provided at its upper end with a part engageable with said element to restrain said assembly against dropout movement, a supporting member rigidly connected near the lower end of said fuse tube, a link arm pivotally connected to said supporting member to provide a knee joint, means for supporting said assembly for pivotal movement on said lower contact to move said assembly away from said retaining element and thus permit pivotal dropout movement of said assembly, said supporting means having a portion extending beyond said knee joint, said assembly including a fuse extracting arm pivotally mounted on said link arm and normally cooperating with said portion to prevent pivotal movement between said link arm and said supporting member, a fuse link extending through said fuse tube and secured to said fuse extracting arm, and Ibiasing means carried by said link arm and acting upon said fuse extracting arm to pivot said fuse extracting arm when said fuse link is ruptured in order to extract the fuse link from the fuse tube and thereafter to permit pivotal movement between said link arm and said supporting member, thereby to permit pivotal dropout movement of said assembly.

10. A cutout of the dropout type comprising a support having upper and lower contacts, a retaining element carried by said upper contact, a fuse tube assembly including a fuse tube provided at its upper end with a part engageable with said element to restrain said assembly against dropout movement, a supporting member rigidly connected near the lower end of said fuse tube, a link arm pivotally connected to said supporting member to provide a knee joint, means for supporting said assembly for pivotal movement on said lower contact to move said assembly away from said retaining element and thus permit pivotal dropout movement of said assembly, said supporting means having a pair of integral, spaced apart extensions extending Ibeyond said knee joint and into overlapping relationship with said link arm, said assembly including a fuse extracting arm pivotally mounted on said link arm and normally cooperating with said extensions to prevent pivotal movement between said link arm and said supporting member, a fuse link extending through said fuse tube and secured to said fuse extracting arm, and a leaf spring carried by said link arm and normally extending between said extensions into engagement with said fuse extracting arm to pivot said fuse extracting arm when said fuse link is ruptured in order to extract the fuse link from the fuse tube and thereafter to permit pivotal movement between said link arm and s-aid supporting member, thereby to permit pivotal dropout movement of said assembly.

1l. A cutout of the dropout type comprising a support having upper and lower contacts, .a retaining element carried by said upper contact, a fuse tube assembly including a fuse tube provided at its upper end with a part engageable with said element to restrain said assembly against dropout movement, a supporting member rigidly connected near the lower end of said fuse tube, a link arm comprising a pair of spaced side walls interconnected by a top wall and pivotally connected to said supporting member to provide a knee joint, means for supporting said assembly for pivotal movement on said lower contact to move said assembly away from said retaining element and thus permit pivotal dropout movement of said assembly, said supporting means having an extension extending bey-ond said knee joint into the space between said side walls and said top wall, a fuseextracting arm pivotally mounted on and extending beneath said link arm normally to maintain said extension within said space in order to prevent pivotal movement between said supporting member and said link arm, a fuse link extending through said fuse tube and secured to said fuse extracting arm, and biasing means carried by said link arm Within said space and acting upon said fuse extracting arm to pivot said fuse extracting arm when said fuse link is ruptured in order to extract the fuse link from the fuse tube and thereafter to permit pivotal movement between said link arm and said supporting member, thereby to permit pivotal dropout movement of said assembly.

12. A cutout of the dropout type comprising a support having upper and lower contacts, a retaining element carried by said upper contact, a fuse tube assembly including a fuse tube provided at its upper end with a part engageable with said element to restrain said assembly against dropout movement, a supporting member rigidly connected near the lower end of said fuse tube, a link arm, comprising a pair of side walls interconnected by a top wall portion, means providing a pivotal connection between said supporting member and said link arm, a pair of coaxial trunnions extending in opposite directions from said side walls, means for supporting said trunnions on said lower contact for pivotal movement to move said part away from said retaining element and thus permit pivotal dropout movement of said assembly, said supporting member including a pair of spaced apart extensions normally extending into the space between the side walls and the top wall of said link arm to prevent pivotal movement between said link arm and said sup porting member, a fuse extracting arm pivotally mounted on said link arm for movement about the axis of said trunnions, and extending along said link arm and said supporting member to retain said extension in said space, a fuse link extending through said fuse tube and secured to said fuse extracting arm, and biasing means carried by said link arm within said space and between said extensions for pivoting said fuse extracting arm about said link arm when said fuse link is ruptured in order to extract the fuse link from the fuse tube and thereafter to permit pivotal movement between said link arm and said supporting member, thereby to permit pivotal drop@ out movement of said assembly.

13. A cutout of the dropout type comprising a support having upper and lower contacts, a retaining element carried by said upper contact, a fuse tube assembly including a fuse tube provided at its upper end with a part engageable with said element to restrain said assembly against dropout movement, a supporting member rigidly connected near the lower end of said fuse tube, a link arm pivotally connected to said supporting member to form a knee joint, means for supporting said assembly for pivotal movement on said lower contact to move said assembly away from said retaining element and thus permit pivotal dropout movement of said assembly, a first spring carried by said support and acting on the upper surface of said link arm in a direction tending to break said knee joint, said assembly including a fuse extracting arm pivotally mounted on said link arm and extending beneath said link arm and said supporting member and normally cooperating with said link arm and said supporting member t-o prevent said knee joint froml breaking, a fuse link extending through said fuse tube and secured to said fuse extracting arm, a leaf spring carried on the under side of said link arm and having a tongue portion engaging said fuse extracting arm in order to pivot said fuse extracting arm in the event that the fuse link is ruptured, thereby to draw an arc between the ruptured ends of the fuse link and thereafter to permit said rst spring to break said knee joint and cause pivotal dropout movement of said assembly, said leaf spring being effective to tension the fuse link prior to rupture independently of the force applied to the link arm by the rst spring, and a contact on said fuse extracting arm in engagement with said tongue portion for providing a low resistance path from the fuse link to said supporting means through the cont-act, the leaf spring and the link arm, thereby avoiding current flow through said knee joint, and said link arm, said supporting member and said fuse extracting arm being so dimensioned that said knee joint is prevented from breaking following fuse link rupture until said fuse extracting arm has moved to a position where it extends at a predetermined angle in excess of forty-five degrees with respect to said link arm.

14. A cutout of the dropout type comprising a support having upper and lower contacts, a retaining element carried by said upper contact, a fuse tube assembly including a fuse tube provided at its upper end with a part engageable with said element to restrain said assembly against dropout movement, a supporting member rigidly connected near the lower end of said fuse tube and extending downward from and at an angle to said fuse tube, a link arm pivotally connected to said supporting member to provide a knee joint, said link arm normally extending in the same general direction as said supporting member, means for supporting said link arm on said lower contact for pivotal movement to move said assembly away from said retaining element and thus permit pivotal dropout movement of said assembly, a biasing spring carried by said support and acting on the upper surface of said link arm in a direction tending to break said knee joint, said assembly including a fuse extracting arm pivotally mounted on said link arm and normally extending beneath said link arm and said supporting member and .cooperating with said link arm and said supporting member to prevent said knee joint from breaking, a fuse link extending through said fuse tube and secured to said fuse extracting arm, and a leaf spring carried on the underside of said link arm and having a tongue portion engaging the fuse extracting arm in order to pivot the fuse extracting arm in the event that the fuse link is ruptured, thereby to draw an arc between the ruptured ends of the fuse link and thereafter to permit said knee joint to break and cause pivotal dropout movement of said assembly, said leaf spring being effective to tension the fuse link prior to rupture independently of the force applied to the link arm by the biasing spring, said extracting arm being effective to prevent breaking of the knee joint until the extracting arm has been pivoted beyond a position extending substantially normal to the fuse tube.

15. A cutout `of the dropout type comprising a support having upper and lower contacts, a retaining element carried by said upper contact, a fuse tube assembly including a fuse tube provided at its upper end with a part engageable with said element to restrain said assembly against dropout movement, a supporting member rigidly connected near the lower end of said fuse tube and extending downward from and at an angle to said fuse tube, a link arm pivotally connected to said supporting member to provide a knee joint, said link arm normally extending in the same general direction as said supporting member, said supporting member including a portion extending beyond said knee joint and underlying said link arm, means for supporting said link arm on said lower contact for pivotal movement to move said assembly away from said retaining element and thus permit pivotal dropout `m-ovement of said assembly, a biasing spring carried by said support 'and acting on said link arm in a direction tending to break said knee joint, said assembly including a fuse extracting arm pivotally mounted on said link arm and normally extending along and cooperating with said portion on said supporting member to prevent said knee joint from breaking, a fuse link extending through said fuse tube and secured to said fuse extracting arm, and biasing means disposed between said link arm and said fuse extracting arm for pivoting said extracting arm when the fuse link is ruptured thereby to extract the fuse link from the fuse tube, said extracting arm being effective to prevent breaking of the knee joint until the extracting arm has been pivoted beyond a position extending substantially normal to the fuse tube.

16. A cutout of the dropout type comprising a support having upper and lower terminals, a retaining elementl carried by the upper terminal, a fuse tube assembly including a fuse tube provided at its upper end with a part engageable with said retaining element to restrain said assembly against dropout movement, a supporting member rigidly connected near the lower end of said fuse tube, a link arm pivotally connected to said supporting member to form a knee joint, means for supporting said link arm on said lower terminal for pivotal movement to move said assembly away from said retaining element and thus permit pivotal dropout movement of said assembly, a fuse extracting arm pivotally mounted on said link arm and normally cooperating with said link arm and said supporting member to prevent said knee joint from breaking, a contact carried by said fuse extracting arm, a leaf spring secured to said link arm and having a tongue portion in engagement with said contact to provide a low resistance path through said link arm to said lower terminal independently of said knee joint, and a fuse link extending through said fuse tube and secured to said fuse extracting arm to normally hold said arm against the action of said leaf spring so that rupture of said fuse link results in the pivoting of said fuse extracting arm as a result of force exerted by the leaf spring, thereby permitting said knee joint to break to effect the pivotal dropout movement of said assembly.

References Cited in the tile of this patent UNITED STATES PATENTS 2,179,749 McCluskey et al Nov. 14, 1939 2,296,991 FOX Sept. 29, 1942 2,324,114 Schultz et al. July 13, 1943 2,328,818 Lindell et al. Sept. 7, 1943 2,331,846 Shultz Oct. 12, 1943 2,362,314 Schultz et al Nov. 7, 1944 2,547,160 Hubbard Apr. 3, 1951 2,611,054 Hubbard Sept. 16, 1952 2,734,964 Edward et al Feb. 14, 1956 FOREIGN PATENTS 444,410 Great Britain Apr. 8, 1935 

